/Engine/Source/Runtime/Engine/Public/Model.h
Groups all nodes in the model into NodeGroups (cached in the NodeGroups object)
void GroupAllNodes ( [ULevel](API\Runtime\Engine\Engine\ULevel) * Level, const [TArray](API\Runtime\Core\Containers\TArray)< class [ULightComponentBase](API\Runtime\Engine\Components\ULightComponentBase) * > & Lights )